The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport. The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

The search for MH370 and ocean surface drift – Part III

Executive summary

Several high-resolution surveillance satellites were tasked to obtain images of the ocean in the vicinity of the 7th arc while the surface search for missing flight MH370 was underway in March 2014. Many objects of interest were seen in several of these images from a wide range of locations at the time, but none led to any successful recoveries. Four of these images, taken just west of the 7th arc in the vicinity of the new search area proposed by ATSB in 2016, have recently been carefully re-examined (Minchin et al. 2017). Three of these images (referred to as PHR4, PHR3 and PHR1) contained 9, 2 and 1 objects, respectively, that were classified as “probably man-made” as well as 28 “possibly man-made” objects. The dimensions of these objects are comparable with some of the debris items that have washed up on African beaches and their location near the 7th arc makes them impossible to ignore. But there is no evidence to confirm that any of these objects (let alone all) are pieces of 9M-MRO (the aircraft flying as MH370).

To completely reject the possibility that any of these objects are pieces of 9M-MRO is difficult to defend. Consequently, we have addressed the obvious question raised by this new piece of uncertain, but plausibly-relevant evidence:

If at least some objects in the images are pieces of 9M-MRO, from where did they drift in the weeks between the disappearance of the aircraft and image capture?

This question is, perhaps surprisingly, potentially more difficult to answer than the ones we addressed in the two reports preceding this one. This is because it requires a very detailed knowledge of the surface currents out in the middle of the ocean where almost no in-situ observations have ever been made. However, thanks to the combined data sets from several types of Earth-observation satellites, coupled with the computational power of Australia’s most powerful super-computer and more than a decade of Government investment in operational ocean modelling, we think we have succeeded.

Taking drift model uncertainty into account, we have found that the objects identified in most of the images can be associated with a single location within the previously-identified region suggested by other lines of evidence. Furthermore, we think it is possible to identify a most-likely location of the aircraft, with unprecedented precision and certainty. This location is 35.6°S, 92.8°E. Other nearby (within about 50km essentially parallel to the 7th arc) locations east of the 7th arc are also certainly possible, as are (with lower likelihood) a range of locations on the western side of the 7th arc, near 34.7°S 92.6°E and 35.3°S 91.8°E. While we cannot be totally sure which of these locations in the southern half of the 2016-proposed search area is most likely, we do have a high degree of confidence that an impact in the southern half of the 2016-proposed search area, near 35°S, is more consistent with detection of debris in the images than is an impact in the northern half.

Summary of imagery analyses for non-natural objects in support of the search for Flight MH370

Results from the analysis of imagery from the PLEIADES 1A satellite undertaken by Geoscience Australia

Geoscience Australia (GA) was asked to assist the Australian Transport Safety Authority (ATSB) in the analysis of a set of four Airbus PLEIADES 1A images. GA received these images for analysis on the 23rd March 2017.

The data was acquired over the Indian Ocean on the 23rd March 2014. The analysis performed by GA was to determine whether the images included objects that were potentially man-made in origin. GA analyses included semi-automatic workflows and a number of potential objects were identified.

The overall location of the study area is shown in Figure 1, and a detailed overview of the four scenes with associated detected objects is shown in Figure 2. Figure 3 details the relationship between the PLEIADES data and other MH370 search-related activities.

The appendix to the report presents a data summary for each of the images. This includes a browse image of each scene, including the object locations, a cross plot of the representative spectral radiances observed in the image, a table of the object locations plus size metrics and an indicative label as to the object’s origin. The detected objects are shown in true colour and in a false colour derived from Principle Components Analysis (PCA) to help distinguish objects from their surroundings.

The search for MH370 and ocean surface drift

Executive summary - Report II

This report explores the possibility that an improved ability to simulate the path taken by the flaperon across the Indian Ocean might yield an improved estimate of the location of the remains of the aircraft on the sea floor.

Our earlier field testing of replicas of the flaperon was unable to confirm numerical predictions by the Direction Generale de L’Armement (DGA) that the flaperon drifted left of the wind. Field testing of a genuine Boeing 777 flaperon cut down to match photographs of 9M-MRO’s flaperon has now largely confirmed the DGA predictions, at least with respect to drift angle. The impact of this information on simulated trajectories across the Indian Ocean is that the July 2015 arrival time at La Reunion is now very easy to explain.

This new information does not change our earlier estimate of the most probable location of the aircraft. It does, however, increase our confidence in that estimate, so we are now even more confident that the aircraft is within the new search area identified and recommended in the MH370 First Principles Review (ATSB 2016).

The proposed new search area has been determined by combining many lines of evidence, the strongest being that the descent began close to the SatCom 7th arc. The following evidence from drift modelling helps indicate where along the 7th arc the aircraft impacted the sea surface:

The July 2015 arrival date of the flaperon at La Reunion island is consistent with impact occurring between latitudes 40°S and 30.5°S.

Arrival off Africa of other debris exclusively after December 2015 favours impact latitudes south of 32°S, as does the failure of the 40-day aerial search off Western Australia to find any floating debris.

Absence of debris findings on Australian shores is only consistent with a few impact latitudes – the region near 35°S is the only one that is also consistent with other factors.

The new search area, near 35°S, comprises thin strips either side of the previously-searched strip close to the 7th arc. If the aircraft is not found there, then the rest of the search area is still likely to contain the plane. The available evidence suggests that all other regions are unlikely.

This report documents the proceedings and outcomes of the First Principles Review meeting on the search for missing Malaysia Airlines flight MH370 held in Canberra from 2 to 4 November 2016. Participants consisted of experts in data processing, satellite communications, accident investigation, aircraft performance, flight operations, sonar data, acoustic data and oceanography. The purpose of the meeting was to reassess and validate existing evidence and to identify any new analysis that may assist in identifying the location of the missing aircraft.

Throughout the search, the ATSB has issued several reports updating the definition of the search area based on analysis progressively refined, or when new information has come to light. This document complements those reports and provides a summary of the detailed analysis of the satellite data combined with new evidence derived from the modelling of the drift of debris from the aircraft.

The experts attending the meeting considered:

The results of the search to date.

Satellite communication metadata and its analysis including methodology, assumptions, limitations, the probability distributions of possible flight paths, and validation results.

Results from simulations and the aircraft manufacturer’s analysis of aircraft performance.

The width of the search area based on what is known about the end of the flight.

Hydro-acoustic analysis potentially relevant to the search.

Failure analysis of recovered debris.

Drift analysis of aircraft debris.

For background information, please refer to the previous ATSB publications available online at www.atsb.gov.au/mh370

The updated independent analysis of the satellite data and the drift analysis consistently identified the most likely impact location of MH370 as being close to the 7th arc[1] (within ~25 NM) and bounded by latitudes of approximately 33°S to 36°S.

There is a high degree of confidence that the previously identified underwater area searched to date does not contain the missing aircraft. Given the elimination of this area, the experts identified an area of approximately 25,000 km² as the area with the highest probability of containing the wreckage of the aircraft. The experts concluded that, if this area were to be searched, prospective areas for locating the aircraft wreckage, based on all the analysis to date, would be exhausted.

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[1] The 7th arc is an arc of possible aircraft positions, equidistant from Inmarsat’s Indian Ocean Region satellite, where the accident aircraft made the final series of satellite communications transmissions. It is the key datum in the search for MH370 and its derivation is described in previous ATSB search area definition reports.

The First Principles Review

In May 2014 the Governments of Australia, Malaysia, and People’s Republic of China agreed that the Australian Transport Safety Bureau (ATSB) would coordinate the underwater search for MH370. The primary objective was to assist the ICAO Annex 13 investigation by locating and positively identifying the aircraft wreckage. It was also essential that any searched area assessed as not containing the aircraft could be discounted with a high degree of certainty.

In November 2016, the high priority underwater search area defined in the ATSB’s previous reports was in its final stages of being searched. As such, the ATSB determined that a review of all available information relating to the search area definition was required. Participants at the three-day meeting held from 2-4 November 2016 at the ATSB office in Canberra included experts from each field of expertise where information was available to assist in the search area determination.

Accordingly, there were representatives at the meeting from all of the organisations participating in the Search Strategy Working Group including Australia’s Defence Science and Technology Group (DST Group), Boeing, Thales, Inmarsat, the National Transportation Safety Board of the US, the Air Accidents Investigation Branch of the UK and the Department of Civil Aviation, Malaysia. In addition, there were representatives from the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Geoscience Australia, Curtin University, Malaysia Airlines and the People’s Republic of China.

The aim of the First Principles Review meeting was to consider the results of the underwater search to date, examine the data and analysis associated with the accident flight, and the definition of the search area. The meeting also focussed on new analysis relating to recovered aircraft debris.

Abbreviated minutes

The first day of the meeting focused on a comprehensive review of the satellite communications (SATCOM) data, and the analysis methods used to estimate the aircraft’s final location. The meeting included presentations from all organisations with subject matter expertise related to the SATCOM system. The review re-examined the detailed assumptions, calculation methods, and validations that led to the definition of the search area. The analyses had been verified using data from previous flights. The meeting participants determined that techniques used were acceptable and the results for the analysis of the accident flight were valid.

The second day of the meeting focused on the debris that was recovered from the islands to the east of Africa and the African coast from Tanzania to South Africa. CSIRO presented the analysis which examined the rate of movement (drift) of the flaperon (found on La Réunion Island in 2015) and other items, and its correlation to drift models. The results of this analysis identified an area of likely origin of the recovered debris (i.e. the aircraft’s impact location). ATSB experts presented conclusions from the examination of the recovered flap section with respect to the likely configuration of the aircraft at the end of flight. The meeting participants determined that the analysis presented on the debris and subsequent results were valid.

The results of the underwater search were also presented including the search methods, completed coverage, sonar data interpretation, quality assurance and confidence in the results. A presentation on the hydro-acoustic data at the time of the accident allowed meeting participants to determine that hydro-acoustic analysis did not contribute any useful new information to the search.

On the third day, the meeting examined how the results of the search to date, the flight path modelling based on the satellite data, the drift modelling and the debris analysis may assist in the definition of any future search activities and the priorities for such activities.

Satellite data

Throughout the search, data from a communications satellite along with aircraft performance data has been used to attempt to reconstruct the flight path of MH370 from the time of the last radar contact. Information recorded by a satellite ground station at the time of handshakes[2] with MH370 was used to estimate the track of the aircraft. SATCOM information from two unanswered ground to air telephone calls was also available. This information showed that the flight continued for approximately five and a half hours after the last radar data.

The calculations identified seven ‘arcs’ which lead to the definition of the search area along the current north-south line of the 7th arc (which is regarded as the primary datum for determining the search area). It was then necessary to define which section of the 7th arc has the highest likelihood of finding the aircraft and the width of the search area to the east and west of the arc; encompassing aircraft performance limits and end of flight scenarios.

The DST Group provided expert analysis of the available SATCOM data relating to MH370. The analysis used models of the Inmarsat SATCOM data, aircraft dynamics, and meteorological data to determine likely flight paths. The DST Group analysis has been published in the book, Bayesian Methods in the Search for MH370. The methodology was subjected to a set of validation experiments to ensure that the set of predicted flight paths aligned with actual flight data for previous flights of the accident aircraft (registered 9M-MRO) and other flights in the air at the same time as the accident. Further burst frequency offset (BFO) analysis performed by DST Group was contained in the ATSB report of 2 November 2016, MH370—Search and debris examination update.

At the First Principles Review meeting, experts discussed their work to refine the analysis and considered the possible analysis techniques, validations and accident result scenarios. Their particular focus was the effect of the sonar search results to date on the probability map for the search area.

Search results and likely aircraft autopilot mode

The DST Group analysis which used a dynamic model of the aircraft, examined five different lateral aircraft autopilot control modes:

1. Constant magnetic heading (CMH).

2. Constant true heading (CTH).

3. Constant magnetic track (CMT).

4. Constant true track (CTT).

5. Lateral navigation (LNAV).

The initial analysis assumed equal likelihood (uniform probability) across the lateral aircraft modes throughout the southern portion of the accident flight. The results of the analysis suggested that based on the satellite data, the aircraft was more likely to be operating at the time in the CTT or LNAV lateral control modes. These lateral control modes generally resulted in the aircraft’s flight path being towards the southern end of the search area. The remaining three lateral control modes generally resulted in the aircraft’s flight path ending north of the CTT and LNAV results, up to 33°S in latitude along the 7th arc.

The southern portion of the search area which mainly encompasses the CTT and LNAV lateral control mode results has been thoroughly searched with underwater assets (deep tow, AUV, and ROV). Based on the results of the underwater search, the probability distribution was updated to reflect the new information of the unsuccessful search which then favoured the other control modes.

Flight crew advice

During the First Principles Review meeting, flight crew with extensive experience on the aircraft type indicated that the aircraft is usually flown in the LNAV or CMH lateral control modes.

This information, combined with the results from the areas already searched to increases the likelihood in the northern section of the probability map in Figure 13.

The analysis of the debris recovered from MH370 indicating that the flaps were likely in a retracted position.

The analysis of the BFO from the final two SATCOM transmissions which indicated that the aircraft was likely to be on an unstable flight path.

Results from recent simulations showed high rates of descent broadly consistent with the BFO analysis. These simulations indicated that the aircraft was likely to be within 15 NM of the 7th arc.

This information provided significantly more weight to the aircraft being located closer to the arc than the ATSB concluded in 2015—probably within 25 NM, with locations closer to the 7th arc a higher likelihood.

This analysis, and the implications for the width of the search area were presented at the First Principles Review meeting. All participants were in general agreement that the distance required to be searched from the arc could be reduced to 25 NM from the 7th arc with a weighting to the west to account for the arc altitude[3].

Drift analysis

More than 20 items of debris have been recovered and identified as likely to be, almost certainly or definitely originating from MH370. The first of these was the flaperon, found on La Réunion Island on 29 July 2015. Other items have been located along the east and south coast of Africa, the east coast of Madagascar and the Islands of Mauritius and Rodrigues in the Indian Ocean. A complete list of recovered items was published by the Malaysian investigation team and can be found at www.mh370.gov.my/index.php/en/.

An oceanographer from CSIRO was involved in the initial sea surface search for MH370 coordinated by the Australian Maritime Safety authority (AMSA). CSIRO continued to assist in the search for MH370 by completing work predicting landfall areas for floating debris, and analysing the drift of recovered debris.

In April 2016, the ATSB commissioned CSIRO to perform a detailed study of the drift of the recovered debris. The final report of this study has been released concurrently with this report and should be read in conjunction with this section. The CSIRO report and can be found on the ATSB website.

The aim of the CSIRO drift study was to determine the probability of locations along the 7th arc (defined by SATCOM analysis as between 45°S and 22°S) being the origin of the recovered debris.

A forward-tracking numerical simulation was created. Within the simulation, flaperons and other modelled debris were deployed on and around the 7th arc and allowed to drift freely. The simulated paths of the debris were calculated and compared against information from three sets of observations:

1. The extensive aerial and surface search conducted between 18 March and 28 April 2014.

2. The absence of debris from MH370 found anywhere along the coast of Australia.

3. The timing and location of parts from MH370 found on islands in the western Indian Ocean and on the east coast of the African continent.

The following is a summary of the results from the CSIRO drift analysis:

1. From the number and size of items found to date from MH370 there was definitely a surface debris field, so the fact that the sea surface search detected no wreckage argues quite strongly that the site where the aircraft entered the water was not between latitudes 32°S[4] and 25°S along the 7th arc. Those latitudes are also contra-indicated by an absence of aircraft parts being found off Africa earlier than December 2015.

2. Latitudes south of 39°S are quite strongly contra-indicated by the arrival times of the flaperon and other debris reaching Africa, and the fact that those items were many while findings anywhere on the Australian coastline were nil.

3. The absence of debris being found on African shores in 2014 suggests that the impact site was likely not north of 25°S.

4. Assuming that the crash was within ~25 NM of the 7th arc (ATSB 2016), this leaves only points between 36°S and 32°S that are less than ~25NM from the arc but outside the area that was searched in late 2014 and early 2015.

5. There is a region within the 36-32°S segment of the 7th arc, near 35°S that is most consistent with all of the following lines of evidence, taken together including:

a. The absence of detections during the 2014 surface search.

b. The absence of findings on the WA coastline.

c. The July 2015 arrival time of the flaperon at La Reunion Island.

d. The December 2015 and onwards (only) arrival times of other debris in the western Indian Ocean.

Residual Probability Map

DST Group have used the Bayesian approach to incorporate multiple sources of analysis into a single probability map, or probability density function (PDF), of the location of the aircraft.

The main PDF is generated from the analysis of the satellite data and the search area width analysis. The residual PDFs show the effects of the other analyses (i.e. search results and drift analysis) on the probabilities.

Figure 11 shows the result of the SATCOM PDF updated with the search results. The areas searched were removed from the PDF. The residual probability is located in areas yet to be searched, with two clear areas of interest: north of the current search area and south of the current search area.

Figure 11. Updated probability distribution with the results of the underwater search.

Source: Google Earth / DST Group

Figure 12 shows the SATCOM PDF with the CSIRO drift study of the flaperon arrival at La Reunion Island likelihood overlaid. The alignment of the high likelihood point of origin of the flaperon from the drift analysis (green) and the peak of the northern SATCOM analysis PDF can be clearly seen (red circle).

Figure 12. Updated probability distribution with the results of the underwater search and the drift analysis results overlaid

Source: Google Earth / DST Group

Figure 13 shows the search probability distribution based on the SATCOM data and CSIRO drift analysis. The section south of the indicative search area (pink box in figure 12) becomes much less favourable once the drift results are incorporated.

Figure 13. Updated probability distribution with the results of the underwater search and the drift analysis

Source: Google Earth / DST Group

Conclusions

1. There is a very high level of confidence in the search results to date in the current indicative search area. The high resolution sonar coverage is very high and the data has been subjected to a very thorough analysis. The area has been searched to a level of confidence >95% without identifying the aircraft debris field.

2. The analysis of the last two SATCOM transmissions, the likely positon of the aircraft’s flaps at impact and results from recent end of flight simulations has allowed a revision of the distance required to be searched away from the 7th arc. 99% of the DST Group analysis results lie within 25 NM to the east and west of the arc.

3. A residual probability map based on the comprehensive satellite communication data analysis and updated with the latest search results and the CSIRO drift analysis identified a remaining area of high probability between latitudes 32.5°S and 36°S along the 7th arc.

4. The participants of the First Principles Review were in agreement on the need to search an additional area representing approximately 25,000 km² (the orange bordered area in Figure 14). Based on the analysis to date, completion of this area would exhaust all prospective areas for the presence of MH370.

The search for MH370 and ocean surface drift

Executive summary - Report 1

This report details the results of a comprehensive attempt to use drift modelling to inform efforts to locate the missing Malaysia Airlines flight MH370 (registered 9M-MRO). It differs from earlier attempts to do this in several important ways, which, along with other developments, have enabled it to come up with a location of the aircraft that is much more precise than we thought was possible.

We have concluded that the northern third (from 36°S to 33°S or perhaps 32°S) of the initial search area uniquely remains prospective. This northern area was partially searched (close to the 7th arc) in the latter half of 2014 and early 2015. Locations outside the searched area, but still within a likely distance from the arc, remain unsearched. The region near 35°S is particularly prospective because there is strong evidence (from Earth-observation satellite data) that this is where, at the time of the accident and for weeks after, the debris field would have been carried north-west for about 500km, away from where the March-April 2014 surface search was conducted and away from the shores of Western Australia (WA). The scenario of a final location near 35°S is the one that is most consistent with:

the absence of debris findings on the WA coastline

the absence of debris findings during the aerial and surface search

the July 2015 arrival time of the flaperon at La Reunion

the December 2015 and onwards (only) arrival times of debris in the western Indian Ocean.

The uncertainty of this finding has been greatly reduced from what was possible earlier by:

measuring the wind-driven drift rate of replica aircraft parts alongside oceanographic drifters (whose travel times across the Indian Ocean are well known), and

using a new ocean model that is informed by very accurate satellite measurements of small perturbations of sea level, yielding estimates of surface currents that have been validated using the global archive of oceanographic drifters.

Are other regions also prospective?

If the flaperon had remained the only piece of debris found we would have to say ‘perhaps’, but now many debris items have been found, we can conclude that regions north of 32°S and south of 39°S are both less likely. Drift modelling suggests that debris items originating north of 32°S would probably have been detected by the surface search, and that items would have probably arrived in Africa before December 2015. Regions south of 39°S are not prospective either, because debris from those regions would more likely have turned up on Australian coastlines than west Indian Ocean ones.

MH370 – Search and debris examination update

Executive summary

This report provides an update to the MH370 search area definition described in previous ATSB reports. It comprises further analysis of satellite data, additional end of flight simulations, a summary of the analysis of the right outboard wing flap, and preliminary results from the enhanced debris drift modelling.

For background information, please refer to the ATSB publications available online at www.atsb.gov.au/mh370:

Definition of underwater search areas, 18 August 2014

Flight Path Analysis Update, 8 October 2014

Definition of Underwater Search Area Update, 3 December 2015.

The Australian Defence Science and Technology (DST) Group[1] conducted a comprehensive analysis of the Inmarsat satellite communications (SATCOM) data and a model of aircraft dynamics. The output of the DST Group analysis was a probability density function (PDF) defining the probable location of the aircraft’s crossing of the 7th arc.

Additional analysis of the burst frequency offsets associated with the final satellite communications to and from the aircraft is consistent with the aircraft being in a high and increasing rate of descent at that time. Additionally, the wing flap debris analysis reduced the likelihood of end-of-flight scenarios involving flap deployment.

Preliminary results of the CSIRO’s drift analysis indicated it was unlikely that debris originated from south of the current search area. The northernmost simulated regions were also found to be less likely. Drift analysis work is ongoing and is expected to refine these results.

7th arc burst frequency offset (BFO) analysis

The final satellite communication (Satcom) transmissions between the Inmarsat Ground station and 9M-MRO occurred at 00:19 on the 8th March 2014. These transmissions were the aircraft logging on to the Satcom system, likely after an interruption to the power that supplies the satellite data unit (SDU) – an integral part of the Satcom system.

The BFO is a function of the Doppler shifts imparted on the communication signal due to the motion of the satellite and the aircraft. The relationship is more complicated than a direct Doppler calculation because the aircraft software contains Doppler compensation that offsets the Doppler shift due to the aircraft motion. Although the aircraft attempts to compensate for its own motion, it does this under the assumption that the communications satellite is in notional geostationary orbit and it does not include the vertical component of the aircraft velocity.

Analysis of the BFO value can provide information about the relative motion between the satellite and the aircraft. Figure 1 shows all the BFO recordings from 9M-MRO. The comprehensive analysis provided by the Defence Science and Technology (DST) Group (Bayesian Methods in the Search for MH370) indicated that the aircraft was likely on a southerly heading at 18:39. From that point until 00:11, all the solutions of the analysis showed a continuing southerly track.

Figure 1: Recorded BFO values throughout the flight

Source: ATSB

This graph illustrates the measured BFO recordings throughout the flight with the appropriate error bars on the measurements. After 18:39 the BFO values follow an approximately linear trend until the final two values at 00:19.

The trend of the BFO values from 18:39 until the 6th arc (00:11) is due to the change in location of the aircraft and can be linearly approximated (Figure 2). If this linear approximation is extrapolated to 00:19, and if neither the Satcom system nor the aircraft flight path were altered after 00:11, a BFO value of approximately 260 Hz would have been expected.

Figure 2: Linear approximation of the BFO values between 18:39 and 00:11

Source: ATSB

This graph illustrates 5 BFO values recorded between 18:39 and 00:11 and the linear approximation of the BFO at 00:19. The first 5 values correspond to the 2nd-6th arcs. During this time the aircraft is likely to be following a relatively constant southerly track. Continuing this linear trend to 00:19, a value of 260Hz would be expected.

The recorded values of the BFO for the two messages at 00:19 were the following:

Table 1: Recorded BFO values at 00:19

Time

Burst Frequency Offset

00:19:29

182 Hz

00:19:37

-2 Hz

To explain this difference between the expected BFO value (260 Hz) and the recorded BFO values (Table 1), an examination was undertaken of the elements that contribute to the BFO.

This analysis includes a number of approximations, and the results should be interpreted as an approximate guide on the range of possible descent rates at the time of the last two SATCOM messages that were sent from 9M-MRO. DST Group intend to publish a more detailed version of the analysis in the near future. It should be noted that small refinements in the analysis may result in descent rate calculations that differ slightly from the values published here.

In the analysis it is assumed that there were no major changes to the satellite system between 00:11 and 00:19. Therefore the contributing elements consist of the:

tolerance or error of the BFO

direction of travel of the aircraft

oven-controlled oscillator warm-up drift

descent rate of the aircraft.

BFO tolerance or error

A statistical analysis of the BFO error from all the 20 previous flights of 9M-MRO identified that the distribution was approximately Gaussian (see DST Group book – link above) with a standard deviation of 4.3 Hz. ±3 standard deviations (12.9 Hz) is a conservative choice for the error.

Direction of flight

For any given speed, the estimated BFO differences can be plotted against the predicted heading of the aircraft (Figure 3). The maximum variation in the BFO differences based solely on change in direction is approximately 20 Hz.

Figure 3: Variation in estimated BFO differences at 00:19 for given track angles and groundspeed

Source: DST Group

This graph indicates that the lowest BFO differences, and therefore the closest to our measured values, would be attained for any given speed by continuing in a southerly direction.

Oscillator warm-up drift

The oven-controlled crystal oscillator (OCXO) maintains the oscillator in the satellite data unit (SDU) at the design temperature. The performance of the OCXO in maintaining the correct temperature directly affects the transmitted frequency. When power is first applied to the SDU, the transient temperature variation associated with the OCXO warming-up causes a variation in the output frequency. This is referred to as warm-up drift.

To further understand this behaviour, the manufacturer of the SDU performed multiple power-up tests on several SDUs. It was observed that individual SDUs exhibit different warm-up drift characteristics. The differences were the magnitude of the frequency deviation, the time to reach steady state as well as the general shape of the curve.

Variations in the time in which the SDU (and OCXO) was not powered, prior to powering on, affected both the magnitude of the drift and the time taken for the frequency to stabilise, however the characteristic (or general shape of the curve) was not affected.

All available information indicated that, after power-up, the SDU in 9M-MRO exhibited a decay characteristic, represented in Figure 4. The values recorded shortly after power up would therefore be greater than the steady state value.

This graph illustrates the warm-up characteristic of the 9M-MRO SDU. After power is restored to the SDU, the OCXO drift results in BFO value being above the steady state value until the OCXO has stabilised.

The maximum OCXO drift value observed in the previous data of 9M-MRO was around 130 Hz and if the power interruption was sufficiently short, the OCXO drift could be negligible.

Descent rate

The remaining element to explain the difference in the predicted BFO value and the recorded BFO value is the descent rate of the aircraft. Analysis shows that at locations consistent with the search area and at the time of the last transmission, the descent rate affects the BFO value at -1.7 Hz per 100 ft/min.

Results of analysis

Due to the uncertainties associated with the end-of-flight scenario, it is not possible to define a specific descent rate from the recorded BFO values. Instead, using the limits of each contributing element, a range of possible descent rates, consistent with the recorded BFO values can be determined.

Case A and Case B below represent the boundary cases for the minimum descent rate and the maximum descent rate respectively. For each transmission at 00:19, Case A applies assumptions that reduce the required rate of descent to match the recorded BFO. Case B does the opposite and applies assumptions which increase the required rate of descent.

In April 2016, the ATSB defined a range of additional scenarios for the manufacturer to simulate in their engineering simulator. Reasonable values were selected for the aircraft’s speed, fuel, electrical configuration and altitude, along with the turbulence level.

The results of the simulation are presented in Figure 6. The results have all been aligned to the point two minutes after the loss of power from the engines. This is the theorised time at which the 7th arc transmissions would have been sent.

Figure 6: Results from simulated scenarios

Source: ATSB

This figure illustrates the resulting flight paths from the simulations performed by the manufacturer and aligned at a point consistent with when the final BTO transmission may have occurred.

The simulations were completed in the manufacturer’s engineering simulator. The engineering simulator uses the same aerodynamic model as a Level D simulator used by the airlines. The simulator is not a full motion simulator but instead is used when a high level of system fidelity is required. The appropriate firmware and software applicable to the accident aircraft can be loaded.

The results of the simulations were that:

The aircraft was capable of travelling rearwards (from the direction of travel) approximately 21 NM.

Simulations that experienced a descent rate consistent with the ranges and timing from the BFO analysis generally impacted the water within 15 NM of the arc.

In some instances, the aircraft remained airborne approximately 20 minutes after the second engine flameout.

In an electrical configuration where the loss of engine power from one engine resulted in the loss of autopilot (AP), the aircraft descended in both clockwise and anti-clockwise directions.

In some simulations, the aircraft exhibited phugoid motion[2] throughout the descent.

Simulations that exhibited less stable flight resulted in higher descent rates and impact with water closer to the engine flameout location. In some simulations, the aircraft’s motion was outside the simulation database. The manufacturer advised that data beyond this time should be treated with caution.

Some of the simulated scenarios recorded descent rates that equalled or exceeded values derived from the final SATCOM transmission. Similarly, the increase in descent rates across an 8 second period (as per the two final BFO values) equalled or exceeded those derived from the SATCOM transmissions. Some simulated scenarios also recorded descent rates that were outside the aircraft’s certified flight envelope.

The results of the scenarios, combined with the possible errors associated with the BTO values indicate that the previously defined search area width of ±40 NM is an appropriate width to encompass all uncontrolled descent scenarios from the simulations.

The simulated scenarios do not represent all possible scenarios, nor do they represent the exact response of the accident aircraft. Rather, they provide an indication as to what response the accident aircraft may have exhibited in a particular scenario. As such, the results are treated with caution, and necessary error margins (or safety factors) should be added to the results.

It was not possible to simulate all likely scenario conditions due to the limitations of the simulator. Specifically, flight simulators are unable to accurately model the dynamics of the aircraft’s fuel tanks. In the simulator, when the fuel tank is empty, zero fuel is available to all systems fed from the tank. However, in a real aircraft, various aircraft attitudes may result in unusable fuel (usually below engine/APU inlets) becoming available to the fuel inlets for the APU/engines. If this resulted in APU start-up, it would re-energise the AC buses and some hydraulic systems. This could affect the trajectory of the aircraft. Similarly, the left and right engines may also briefly restart, affecting the trajectory.

Drift modelling update

To assist with the underwater search for 9M-MRO, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) undertook an analysis of existing ocean data from the Global Drifter Program[3]. The analysis used the behaviour of drogued and undrogued drifters[4], as well as numerical simulations using ocean models. The purpose of this work was to trace any recovered debris to its likely point of origin. However, a drifter’s geometry and buoyancy is not generally representative of aircraft debris and it was considered that the drift characteristics might also be different. To account for this difference, the CSIRO engaged in field work, studying how aircraft debris moves through the water compared to drifters, with regard to wind and ocean currents. This data was incorporated into numerical simulations in order to predict the drift behaviour of aircraft debris with more confidence.

As part of the ongoing field testing, the drift behaviour of replica flaperons and other recovered aircraft parts is being assessed. Replica flaperons were constructed with dimensions and buoyancy approximately equal to that of the recovered flaperon (Figure 7), which was float-tested during the detailed examinations in France. The replica flaperons were deployed into a bay for short term tests during various weather conditions. Longer term tests were then performed in the open ocean. For comparison, undrogued drifters were deployed alongside the flaperons. Drogued drifters were also used, because they move predominantly with the currents, as opposed to wind and waves. Data for currents was then able to be subtracted from the flaperons’ drift data so that wind and wave behaviour could be assessed in isolation.

Field tests demonstrated that the replica flaperons drift similarly to undrogued drifters:

In low wind conditions, the flaperons move slightly faster than undrogued drifters due to the energy absorbed from waves.

In higher winds, the energy absorbed from waves was less significant, and the flaperons’ behaviour was analogous to the undrogued drifters’.

The replica flaperons presented their raised trailing edge to the wind, allowing waves to propel them in the wind direction. If waves tipped or turned the flaperons, the wind quickly reoriented them, so the direction of movement remained consistent.

Replicas of two other recovered items of debris drifted at a rate that was practically indistinguishable from undrogued oceanographic drifters in all wind conditions. Therefore, the trajectories of undrogued oceanographic drifters were valid for use in the analysis.

Preliminary results from the updated drift analysis indicated that the current search area was a possible origin for the recovered debris.

Using the collected field data, a new forward-tracking numerical simulation was performed. Within the simulation, flaperons were deployed on and around the current search area and allowed to drift freely. Results after 500 days of simulated drift are presented in Figure 8. For comparison, Figure 9 shows the results of a simulation where the original undrogued drifter model was used. By comparing the two figures, it can be seen that the flaperons generally moved further west within 500 days due to the extra speed at low winds.

Small errors in the simulation can result in large divergences over time. As such, an examination of the debris behaviour in the first months after the accident was conducted.

Figure 10 illustrates the starting location of the simulated drifters along the 7th arc. After eight months of simulated drift (Figure 11), some initial conclusions can be drawn about the drifter’s path with respect to debris discovered to date. A significant number of drifters arrived on the coast of Western Australia. Similarly, a number of drifters had arrived on the coast of Africa. The colour of each drifter identifies its starting location as marked along the arc.

Drifters starting in the southern half of the current search area or below (dark blue, green, light blue) can be observed on and around the coast of Western Australia, with many drifting towards Tasmania. No debris has been discovered on the Australian coast. This indicates that a starting location within the current search area, or further north, is more likely.

A significant number of red drifters have already reached the coast of Madagascar and mainland Africa. This is not consistent with the time at which debris was discovered. The first item of debris was not discovered on Reunion Island until 16 months after the accident. This suggests a reduced likelihood of debris originating from the northernmost areas shown in Figure 10 (red and white coloured regions).

Refinement of the drift analysis is continuing. Flaperon replicas are currently deployed in the open ocean along with drogued and undrogued drifters, and replicas of smaller debris. This is to study the longer-term drift behaviour of the parts in conditions similar to those expected in the Indian Ocean. The long-term tests may provide additional improvement to the simulations and confidence in the backtracking results.

A significant number of drifters from the light blue and green areas have made landfall on the West Australian coast. Similarly, drifters from the red and white areas have begun to make landfall on the African coastline. Neither are consistent with times and/or locations at which MH370 debris was discovered, therefore reducing the likelihood of debris originating from these locations.

Analysis

Damage to the internal seal pan components at the inboard end of the outboard flap was possible with the auxiliary support track fully inserted into the flap. That damage was consistent with contact between the support track and flap, with the flap in the retracted position. The possibility of the damage originating from a more complex failure sequence, commencing with the flaps extended, was considered much less likely.

With the flap in the retracted position, alignment of the flap and flaperon rear spar lines, along with the close proximity of the two parts, indicated a probable relationship between two areas of damage around the rear spars of the parts. This was consistent with contact between the two parts during the aircraft breakup sequence, indicating that the flaperon was probably aligned with the flap, at or close to the neutral (faired) position.

Numerous other discrete areas of flap damage were analysed. Some of the damage was consistent with the flaps in the retracted position, while other areas did not provide any useful indication of the likely flap position. It was therefore concluded that:

The right outboard flap was most likely in the retracted position at the time it separated from the wing.

The right flaperon was probably at, or close to, the neutral position at the time it separated from the wing.

Debris summary and analysis

Currently, more than 20 items of debris have been brought to the attention of and are of interest to the investigation team. The items have been located along the east and south coast of Africa, the east coast of Madagascar and the Islands of Mauritius, Reunion and Rodrigues in the Indian Ocean. A list of items recovered was published by the Malaysian investigation team and can be found at www.mh370.gov.my/index.php/en/.

The right flaperon has been examined by the French Judiciary and confirmed to have originated from 9M-MRO. Six further items of debris have previously been examined by the ATSB, comprising a:

section of the right outboard flap fairing

panel section from the right horizontal stabiliser

piece of engine cowling

closet panel section from the closet adjacent to door R1

inboard section of the right outboard flap

trailing edge section of the left outboard flap.

Both flap sections had unique identification numbers that were able to be linked, through manufacturing records, to 9M-MRO. The remaining examined items were confirmed as Boeing 777 parts and had identifying features linking them to a Malaysian Airlines origin, however there were no unique identifiers to link the parts directly to 9M-MRO. The parts were therefore determined to have almost certainly originated from 9M-MRO, given that the likelihood of originating from another source is very remote. The ATSB debris examination reports are available at www.atsb.gov.au/mh370-pages/updates/reports/.

Outboard flap failure analysis

The recovered right, outboard wing flap section (Figures 12, 13 and 14) was examined for any evidence of interaction with mechanisms, supports and surrounding components that may indicate the state of flap operation at the time of fracture and separation from the wing. The purpose of the examination was to inform the end-of-flight scenarios being considered by the search team. The most significant items of evidence in relation to this are documented below.

Flap position

The trailing edge outboard wing flaps form part of the aircraft’s high-lift control system and are deployed to alter the shape of the aircraft wing, improving lift at lower aircraft speeds during takeoff, approach and landing. The outboard wing flaps have defined stages of flap deployment between ‘up’ (retracted / cruise position) and 30-units of extension (landing position).

A fibreglass and aluminium seal pan is located at the inboard end of the outboard flap. It houses the inboard auxiliary support, comprising a deflection control track (support track) and carriage assembly. The support track is affixed to the rear of the wing. Using rollers in the carriage assembly, the inboard end of the flap is guided along the support track as the flap moves through its deflection range. The track is fully inserted into the flap in the ‘up’ position and progressively withdrawn from the flap as the flaps are deployed (Figure 15). The inboard auxiliary support track and carriage assembly were not present with the recovered debris.

Two adjacent aluminium stiffeners within the inboard seal pan area exhibited impact damage. The damage was significant because it was indicative of impact damage and the only component in the vicinity of the stiffeners, capable of independent movement within the seal pan, was the support track. Measurements of the support track position at the various stages of flap deployment, indicated that the track would have to be fully inserted into the flap in the retracted position to be adjacent to the damaged stiffeners (Figures 16, 17 and 18).

An outwards-fracture of the fibreglass seal pan initiated at a location adjacent to the damaged aluminium stiffeners (Figure 19). The damage was most likely also caused by impact from the support track. That damage provided further evidence of the support track position within the flap seal pan cavity, indicating that the flaps were retracted at the point of fracture and separation from the wing.

Contact damage between the flaperon and outboard flap

The flap seal pan was also fractured adjacent to the rear spar. The fracture resulted from external impact, puncturing the fibreglass and plastically deforming the supporting aluminium structure within the seal pan cavity (Figure 20). Comparable damage was noted at the outboard, rear spar and surrounding structure of the adjacent flaperon (Figure 21). It was noted that the two areas in question are aligned when the flaps are in the retracted position, with a significant offset existing at other stages of flap extension (Figure 22).

Acknowledgements

The ATSB would like to acknowledge the following organisations for their input and continued assistance with the analysis:

Air Accidents Investigation Branch (UK)

Australian Bureau of Meteorology

Australian Defence Science and Technology Group

Boeing

Commonwealth Scientific and Industrial Research Organisation

Department of Civil Aviation, Malaysia

Inmarsat

Malaysian Airlines Berhad

Malaysian Ministry of Transport

National Transportation Safety Board (US)

Thales.

Those involved have dedicated many hours outside of normal duties to advance the collective understanding of the event. The main focus has always been in finding the aircraft to assist the Malaysian investigation team and to bring closure to the families of the passengers and crew of MH370.

These debris examination reports are released with the concurrence of the Malaysian ICAO Annex 13 Safety Investigation Team for MH370.

Debris Report 1 (19 April 2016)

Published: 19 April 2016 (amended 17 August 2017)

Debris examination – update No. 1

Identification of two items of debris recovered in Mozambique

Introduction

On 27 December 2015 and 27 February 2016, two items of debris were independently found, approximately 220km apart, on the Mozambique coast. Both items were delivered to the relevant Civil Aviation Authorities in Mozambique and South Africa in early March 2016. Assistance from the Australian Transport Safety Bureau (ATSB) was requested by the Malaysian Government in the formal identification of the items to determine if they came from the Malaysia Airlines Boeing 777 aircraft, registered 9M-MRO, operating as MH370.

The parts were packaged in Mozambique and South Africa respectively and delivered safe-hand to the ATSB in their original packaging, in the custody of the ICAO Annex 13 Safety Investigation Team members.

The following is a brief summary of the outcomes from the debris examination. This debris examination summary is released with the concurrence of the Malaysian ICAO Annex 13 Safety Investigation Team for MH370.

Quarantine and marine ecology

On arrival into Australia, both parts were quarantined at the Geoscience Australia facility in Canberra. The parts were unwrapped and examined for the presence of marine ecology and remnants of biological material. Visible marine ecology was present on both parts and these items were removed and preserved. The parts were subsequently cleaned and released from quarantine.

Identification

Part No. 1

The first part was initially identified from a number stencilled on the part (676EB), as a segment from a Boeing 777 flap track fairing (Fairing No. 7) from the right wing (Figure 1). All measurable dimensions, materials, construction and other identifiable features conformed to the applicable Boeing drawings for the identified fairing.

The 676EB stencil font and colour was not original from manufacture, but instead conformed to that developed and used by Malaysia Airlines during painting operations (Figure 2). The part had been repainted, which was consistent with the operator’s maintenance records for 9M-MRO.

Part No. 2

The second part was primarily identified from images showing the materials, construction and “NO STEP” stencil, as a segment of a Boeing 777 RH horizontal stabilizer panel (Figure 3). All measurable dimensions, materials, construction and other identifiable features conformed to the Boeing drawings for the stabiliser panel.

The part was marked on the upper surface in black paint with “NO STEP”. The font and location of the stencil were not original from manufacture, however the stencilling was consistent with that developed and used by Malaysia Airlines (Figure 4).

A single fastener was retained in the part. The fastener head markings identified it as being correct for use on the stabiliser panel assembly. The markings also identified the fastener manufacturer. That manufacturer’s fasteners were not used in current production, but did match the fasteners used in assembly of the aircraft next in the production line (405) to 9M-MRO (404) (Figure 4).

Figure 3: Location of horizontal stabiliser panel No. 3 upper

Source: Boeing 777 Parts Catalogue (modified by ATSB)

Figure 4: Stabiliser panel “NO STEP” stencil and fastener comparison

Source: ATSB, Boeing

Conclusions

At the time of writing, ongoing work was being conducted with respect to the marine ecology identification as well as testing of material samples. The results from these tests will be provided to the Malaysian investigation team once complete. Nevertheless, from the initial examination it was concluded that:

Part No. 1 was a flap track fairing segment, almost certainly from the Malaysia Airlines Boeing 777 aircraft, registered 9M-MRO.

Part No. 2 was a horizontal stabiliser panel segment, almost certainly from the Malaysia Airlines Boeing 777 aircraft, registered 9M-MRO.

Debris Report 2 (12 May 2016)

Debris examination – update No. 2

Identification of two items of debris recovered from the beaches in South Africa and Mauritius

Introduction

On 22 and 30 March 2016, two items of debris were independently found on beaches at Mossel Bay, South Africa and Rodrigues Island in Mauritius. Both items were delivered to the relevant Civil Aviation Authorities in South Africa and Mauritius. Assistance from the Australian Transport Safety Bureau (ATSB) was requested by the Malaysian Government in the formal identification of the items to determine if they came from the Malaysia Airlines Boeing 777 aircraft, registered 9M-MRO, operating as MH370.

The items were packaged in South Africa and Mauritius respectively and delivered safe-hand to the ATSB in their original packaging, in the custody of the ICAO Annex 13 Safety Investigation Team members.

This document (Update 2) is a brief summary of the outcomes from the identification of these items, designated as Part numbers 3 and 4. It follows the identification of Part numbers 1 and 2, the outcomes of which were released by the ATSB in Update 1 on 19 April 2016. This debris identification summary is released with the concurrence of the Malaysian ICAO Annex 13 Safety Investigation Team for MH370.

Quarantine and marine ecology

On arrival into Australia, both parts were quarantined at the Geoscience Australia facility in Canberra. The parts were unwrapped and examined for the presence of marine ecology and remnants of biological material. Visible marine ecology was present on both parts and these items were removed and preserved. The parts were subsequently cleaned and released from quarantine.

Identification

Part No. 3

Part number 3 was initially identified from the partial Rolls-Royce stencil as a segment from an aircraft engine cowling. The panel thickness, materials and construction conformed to the applicable drawings for Boeing 777 engine cowlings.

There were no identifiers on the engine cowling segment that were unique to 9M-MRO, however the Rolls-Royce stencil font and detail did not match the original from manufacture. The stencil was consistent with that developed and used by Malaysia Airlines and closely matched exemplar stencils on other Malaysia Airlines Boeing 777 aircraft (Figure 1).

There were identical inboard and outboard stencils present on the cowlings of each of the engines and the location of the stencils was found to vary between engines. Taking that into consideration, there were no significant differentiators on the cowling segment to assist in determining whether the item of debris was from the left or right side of the aircraft, or the inboard or outboard side the cowling.

On 17 May 2016, the ATSB was provided with an earlier photograph of the item, taken on 23 December 2015. This photograph showed the part was significantly colonised by barnacles at the time it arrived on the beach (Figure 3).

Part No. 4

Part number 4 was preliminarily identified by the decorative laminate as an interior panel from the main cabin. The location of a piano hinge on the part surface was consistent with a work-table support leg, utilised on the exterior of the Malaysia Airlines Door R1 (forward, right hand) closet panel (Figure 2). The part materials, dimensions, construction and fasteners were all consistent with the drawing for the panel assembly and matched that installed on other Malaysia Airlines Boeing 777 aircraft at the Door R1 location.

There were no identifiers on the panel segment that were unique to 9M-MRO, however the pattern, colour and texture of the laminate was only specified by Malaysia Airlines for use on Boeing 747 and 777 aircraft. There is no record of the laminate being used by any other Boeing 777 customer.

Figure 1: Comparison of Boeing 777 engine cowling stencils

Note the thickness of the “ROYCE” lettering and the serif geometry on the main ‘R’s (enlarged for ease of comparison).

Conclusions

At the time of writing, work was ongoing with respect to the marine ecology samples. The results from these tests will be provided to the Malaysian investigation team once complete. In terms of the identification of the two items of debris, it was concluded that:

Part No. 3 was a Malaysia Airlines Boeing 777 engine cowling segment, almost certainly from the aircraft registered 9M-MRO.

Part No. 4 was a Malaysia Airlines Boeing 777 panel segment from the main cabin, associated with the Door R1 closet, almost certainly from the aircraft registered 9M-MRO.

Debris Report 3 (15 September 2016)

Published: 15 September 2016 (amended 17 August 2017)

Debris examination – update No. 3

Identification of large flap section recovered off the Tanzanian coast

Introduction

On 20 June 2016, a large item of debris was found on the island of Pemba, off the coast of Tanzania. Preliminary identification from photographs indicated that the item was likely a section of Boeing 777 outboard flap (Figure 1).

Assistance from the Australian Transport Safety Bureau (ATSB) was requested by the Malaysian Government in the formal identification of the item, to determine if the item came from the Malaysia Airlines aircraft, registered 9M-MRO and operating as MH370. The Malaysian investigation team secured the item of debris and arranged shipping to the ATSB facilities in Canberra.

This document (Update 3) is a brief summary of the outcomes from the identification of the item, designated as Part number 5. It follows the identification of Part numbers 1 through 4, the outcomes of which were released by the ATSB in Updates 1 and 2, available on the ATSB website at www.atsb.gov.au/mh370.

This debris identification summary is released with the concurrence of the Malaysian ICAO Annex 13 Safety Investigation Team for MH370.

Identification

Part No. 5

Part number 5 was preliminarily identified from photographs as an inboard section of a Boeing 777 outboard flap. On arrival at the ATSB, several part numbers were immediately located on the debris that confirmed the preliminary identification. This was consistent with the physical appearance, dimensions and construction of the part.

A date stamp associated with one of the part numbers indicated manufacture on 23 January 2002 (Figure 2), which was consistent with the 31 May 2002 delivery date for 9M-MRO.

All of the identification stamps had a second “OL” number, in addition to the Boeing part number, that were unique identifiers relating to part construction. The Italian part manufacturer recovered build records for the numbers located on the part and confirmed that all of the numbers related to the same serial number outboard flap that was shipped to Boeing as line number 404. Aircraft line number 404 was delivered to Malaysia Airlines and registered as 9M-MRO.

Based on the above information, the part was confirmed as originating from the aircraft registered 9M-MRO and operating as MH370.

Figure 1: Inboard section of outboard flap (inverted)Source: ATSB

Figure 2: Exemplar part number and date stampSource: ATSB

Further analysis

At the time of writing, the flap section was being examined for any evidence of interaction with mechanisms, supports and surrounding components (such as the flaperon, which abuts the inboard end of the outboard flap) that may indicate the state of flap operation at the time of separation from the wing. This information may contribute to an increased understanding of end of flight scenarios.

Conclusions

It was confirmed that Part No. 5 was the inboard section of a Boeing 777 right, outboard flap, originating from the Malaysia Airlines aircraft registered 9M-MRO.

Debris Report 4 (22 September 2016)

Published: 22 September 2016

Debris examination – update No. 4

Preliminary examination of two items of debris recovered near Sainte Luce, Madagascar

Introduction

Two items of fibreglass-honeycomb composite debris were recovered near Sainte Luce on the south-east coast of Madagascar, having reportedly washed ashore in February 2016. They were hand-delivered to the Australian Transport Safety Bureau on 12 September 2016. The items were initially reported in the media as being burnt.

This document summarises the ATSB’s preliminary examination of the items for any evidence of exposure to heat or fire.

Examination

No manufacturing identifiers, such as a part numbers or serial numbers were present on either item, that may have provided direct clues as to their origin. At the time of writing, the items had not been identified and work in this respect is ongoing.

A dark grey colouration was present on a significant proportion of both sides of each item (Figures 1, 2 and 3). Detailed examination of these areas showed that the colour related exclusively to a translucent resin that had been applied to those surfaces (Figure 4).

A cross section through the panel showed a clear delineation between the dark resin and the other surface coatings without any evidence of gradual transition. The lighter grey surface areas resulted from a thinner film of the same resin applied over an off-white background. Figure 5 shows the cross section directly and Figure 6 shows the same section at an oblique angle. This confirmed that the dark colour of the coating was an inherent property of the resin, and not the result of exposure to heat or fire.

Despite no evidence of overall gross heat damage, two small (<10mm) marks on one side of the larger item and one on the reverse side were identified as damage resulting from localised heating (Figures 2 and 3). A burnt odour emanating from the large item was isolated to these discrete areas. The origin and age of these marks was not apparent. However, it was considered that burning odours would generally dissipate after an extended period of environmental exposure, including salt water immersion, as expected for items originating from 9M-MRO.

Summary

The following findings were made during a preliminary examination of two items of composite debris, recovered near Sainte Luce, Madagascar. At the time of writing, work is ongoing to determine the origin of the items, specifically, whether they originated from a Boeing 777 aircraft.

The dark grey colouration on the outer surfaces of the items related to an applied resin and was not the result of exposure to heat or fire.

Three small marks on the larger item were indicative of localised heating. The age and origin of these marks was not apparent.

Debris Report 5 (7 October 2016)

Published: 7 October 2016 (amended 17 August 2017)

Debris examination – update No. 5

Identification of wing trailing edge debris recovered from Mauritius

Introduction

An item of composite debris was recovered on the island of Mauritius around 10 May 2016. The item profile was consistent with the trailing edge of an aircraft wing. The item was subsequently collected by a member of the Malayisan investigation team and hand-delivered to the Australian Transport Safety Bureau for identification.

This document is a brief summary of the item identification, designated part number 6. It follows the previous identification and examination reports available on this website at www.atsb.gov.au/mh370. This summary is released with the concurrence of the Malaysian ICAO Annex 13 Safety Investigation Team for MH370.

Identification

Part No. 6

A part number was identified on a section of the debris, identifying it as a trailing edge splice strap, incorporated into the rear spar assembly of a Boeing 777 left outboard flap. This was consistent with the appearance and construction of the debris.

Adjacent to the part number was an “OL” part identifier, similar to those found on the right outboard flap section (Examination update 3). The flap manufacturer supplied records indicating that this identifier was a unique work order number and that the referred part was incorporated into the outboard flap shipset line number 404 which corresponded to the Boeing 777 aircraft line number 404, registered 9M-MRO and operating as MH370.

Conclusion

At 1722 Coordinated Universal Time on 7 March 2014, Boeing 777-200ER aircraft, registered 9M-MRO and operating as Malaysia Airlines Flight MH370, disappeared from air traffic control radar and a search was commenced by Malaysian authorities. The aircraft had taken off from Kuala Lumpur, Malaysia on a scheduled passenger service to Beijing, China with 227 passengers and 12 crew on board.

Under Annex 13 to the Convention on International Civil Aviation Aircraft Accident and Incident Investigation (Annex 13) Malaysia, as the country of registration, has investigative responsibility for the accident.

On 31 March 2014, the Malaysian Government accepted the Government of Australia’s offer to take the lead in the search and recovery operation in the southern Indian Ocean in support of the Malaysian accident investigation. This assistance and expertise will be provided through the accredited representative mechanism of Annex 13.

In accordance with paragraphs 5.23 and 5.24 of Annex 13, on 1 April 2014, the Australian Transport Safety Bureau (ATSB) appointed an accredited representative and a number of advisors to the accredited representative (ATSB investigators). These investigators’ work will be undertaken as part of an External Investigation under the provisions of the Australian Transport Safety Investigation Act 2003.

The Malaysian Ministry of Transport is responsible for and will administer the release of all investigation reports into this accident. Information on the investigation is available from the following websites:

MH370 - Definition of Underwater Search Areas

Released: 3 December 2015

Summary

This report provides an update to the MH370 search area definition, described in previous ATSB reports. For background information, please see the ATSB publications MH370 - Definition of underwater search areas, 18 August 2014 and Flight Path Analysis Update, 8 October 2014 under the tabs on this web page.

Analysis of available data has been ongoing since the search for MH370 commenced. Initial results assisted the search and rescue mission, and later refinements have formed the basis for the underwater search areas.

The Australian Defence Science and Technology (DST) Group conducted a comprehensive analysis of the available data. The analysis used models of the Inmarsat satellite communications (SATCOM) data and a model of aircraft dynamics. Recorded meteorological data (wind and air temperature) were also modelled in the analysis. The SATCOM model was calibrated using SATCOM data and flight data from B777 flights including previous flights of the accident aircraft.

Validation experiments were conducted to ensure that predictions aligned with actual flight data. The output of the DST Group analysis was a probability density function (PDF) defining the probable location of the aircraft’s crossing of the 6th arc. These results were then extrapolated to the 7th arc. The analysis indicated that the majority of solutions only contained one significant turn after the last recorded radar data. DST Group have written a book called Bayesian methods in the search for MH370 detailing the entire analysis.

Performance analysis by Boeing produced a series of achievable ranges, with time intervals, for different cruise altitudes. It was noted that maintaining a constant altitude of FL350 or higher gave range values that closely matched the region on the arc corresponding to the DST Group analysis results. The DST Group and Boeing results were obtained independently and it is significant that they were in general agreement.

In contrast to the series of data points that were recorded from the SATCOM system, only the following indirect information was available to assist the ATSB in determining the end-of-flight scenario and therefore determine a search area width:

probable aircraft systems status

simulator results

review of previous accidents

glide distance.

The original ATSB underwater search area definition report published in August 2014 identified a width of 20 NM behind the arc and 30 NM forward of the arc as the priority search area width. This primary priority width has been adjusted to make it symmetrical about the arc (20 NM on both sides). The ATSB has also defined and prioritised additional search area widths.

The probability distribution of the location of the aircraft is shown in Figure 1.

Figure 1: Probability distribution of the location of MH370

Ongoing work:

Any further evidence that becomes available, and may be relevant to refining the search area,will be considered.

Recent refinement to the analysis has given greater certainty about when the aircraft turned south into the Indian Ocean and has produced a better understanding of the parameters within which the satellite ground station was operating during the last flight of MH370. The latest analyses indicates that the underwater search should be prioritised further south within the wide search area for the next phase of the search. The ATSB has published MH370 – Flight path analysis update to supplement the previously released report MH370 – Definition of Underwater Search Areas, which describes the continuing work.

MH370 - Definition of Underwater Search Areas

Summary

On 8 March 2014, flight MH370, a Boeing 777-200ER registered 9M-MRO, lost contact with Air Traffic Control during a transition of airspace between Malaysia and Vietnam. An analysis of radar data and subsequent satellite communication (SATCOM) system signalling messages placed the aircraft in the Australian search and rescue zone on an arc in the southern part of the Indian Ocean. This arc was considered to be the location where the aircraft’s fuel was exhausted.

A surface search of probable impact areas along this arc, coordinated by the Australian Maritime Safety Authority, was carried out from 18 March – 28 April 2014. This search effort was undertaken by an international fleet of aircraft and ships with the search areas over this time progressing generally from an initial southwest location along the arc in a north-easterly direction. The location of the search areas was guided by continuing and innovative analysis by a Joint Investigation Team of the flight and satellite-communications data. This analysis was supplemented by other information provided to ATSB during this period. This included possible underwater locator beacon and hydrophone acoustic detections.

No debris associated with 9M-MRO was identified either from the surface search, acoustic search or from the ocean floor search in the vicinity of the acoustic detections. The ocean floor search was completed on 28 May 2014.

Refinements to the analysis of both the flight and satellite data have been continuous since the loss of MH370. The analysis has been undertaken by an international team of specialists from the UK, US and Australia working both independently and collaboratively. Other information regarding the performance and operation of the aircraft has also been taken into consideration in the analysis.

Using current analyses, the team has been able to reach a consensus in identifying a priority underwater search area for the next phase of the search.

The priority area of approximately 60,000 km2 extends along the arc for 650 km in a northeast direction from Broken Ridge. The width of the priority search area is 93 km. This area was the subject of the surface search from Day 21-26.

Work is continuing with refinements in the analysis of the satellite communications data. Small frequency variations can significantly affect the derived flight path. This ongoing work may result in changes to the prioritisation and locale of search activity.

Updated: 18 August 2014

Since the public release of the report MH370 – Definition of Underwater Search Areas on 26 June 2014, the ATSB has received a number of queries about some of the technical details contained in the report. The queries have been made directly to the ATSB or through the Chief Commissioner’s blog, InFocus, on the ATSB website.

As a result of the queries, the ATSB is today releasing an updated version of the report to clarify a number of technical aspects. The changes to the report are detailed in the Addendum on the inside cover.

Updated: 8 October 2014

Recent refinement to the analysis has given greater certainty about when the aircraft turned south into the Indian Ocean and has produced a better understanding of the parameters within which the satellite ground station was operating during the last flight of MH370. The latest analyses indicates that the underwater search should be prioritised further south within the wide search area for the next phase of the search. The ATSB has published MH370 – Flight path analysis update to supplement the previously released report MH370 – Definition of Underwater Search Areas, which describes the continuing work.